Lapping thread ring gauge



April 1952 A. E. LANGMAID ETAL 2,591,167

LAPPING THREAD RING GAUGE Filed Sept. 25, 1948 2 SHEETSSHEET 1 41 A/ F30 K 4 o Inventors: AlvzinE iLarzymaz'd Rabert/Lfihwm Their AlorneyApril 1, 1952 A. LANGMAID ET AL- LAPPING THREAD RING GAUGE 2 SHEETSSHEET2 Filed Sept. 23, 1948 Inventors:

AZvirvfilLan/gm/mid Patented Apr. 1, 1952 LAPPING THREAD RING GAUGEAlvin E. Langmaid, Bloomfield, and Robert A. Bloom, Hartford, Conn.

Application September 23, 1948, Serial No. 50,812

9 Claims. (Cl. 51 -32) This invention relates to ring gauges of the typeemployed for testing threads of screws to determine, their accuracy tothe degree of perfection demanded by modern refinements ofinterchangeability.

The primary object is to provide means whereby thread forms may beproduced in certain gauge parts of extremely hard material by lappingoperations only. I

'With this and other objects in view which will become apparent in thefollowing disclosure, the invention consists of mechanism including anovel form and arrangement of parts which are fully explained in saiddisclosure and illustrated in the accompanying drawings while the scopeof the invention is defined by the appended claims.

In the drawings,

Figure 1 is a view of a ring gauge constructed in accordance with theinvention.

Figure 2 is a sectional view on line 22 of Fi 1.

Figure 3 is a longitudinal sectional view of a holder and associatedparts employed for a lapping operation.

Figure 4 is a left end view of the assembly shown in Fig. 3.

Figure 5 is a view similar to Fig. 4 but with a cover plate removed.

Figure 6 is an enlarged detail view of certain assembled parts shown inFig. 5.

Figure is a sectional view on line l-'I of Fig. 3.

Figure 8 is a detail view showing a method of assembling finished partsto form a thread ring gauge, and

Figures9, 10 and 11 are detail views hereinafter more fully explained.

Referring to the drawings, the thread ring gauge illustrated in Fig. 1comprises a body member I, centrally bored at 2 to receive a pluralityof suitably threaded circular ring sectors 3. These ring sectors, inblank form (see Figs. 9 and 10) are obtained with accurate andsubstantially identical contours by cutting a hollow cylinder (Fig. 9)into three equal parts with beveled or relieved corners as at 4 adjacenttheir inner peripheral surface which subsequently is helically groovedto form threads by a lapping operation. Each ring sector 3 is locatedwithin the body member I, as in Figs. 1 and 2, with its outer segmentalperipheral surface 5 in contact with the matching peripheral wall ofbore 2 except at intermediate intervals where the wall of bore 2 isrelieved to provide space areas 6 for reception of a film of solder as Iwhich is applied to secure each ring sector rigidly in its requiredposition.

It will be apparent that body member I may be substantially like wellknown forms of ring gauges such for example as that established byAmerican Gauge Design standards. Thus also provision for adjustabilityof gauge diameter if desired may consist of the conventional arrangementwherein the ring gauge or body member I is parted by a slot 8 extendedfrom the periphery of the ring to the central bore 2, while similarly,slots as 9 and It may be extended from the bore but terminated atsuitably placed stop holes. II and I2 respectively. This arrangementserves to impart and distribute resiliency throughout the body of thering member so as to permit flexing thereof as may be eiiected by screwadjusting means I3 housed in bore l4 which extends through the bodymember in intersecting relation to slot 8, all in accordance withstandard design well known in the art.

Means will now be described for holding ring sectors 3 precisely inrequired relation within body member I while the securing film of solderI is applied within the relief intervals 6. For this purpose a fixtureemployed may comprise a base 9' having secured therein an uprightthreaded plug I0 and also three upright pins II. A set screw I2 servesto secure in place whatever plug as I0 may be appropriate to theparticular thread form of a set of ring sectors which is to be assembledand secured in a body member I. It will be apparent that the threads ona plug I0, by suitable engagement while in a common plane withcorrespondingly formed threads on the ring sectors will locate thelatter in their correct relative positions circumferentially of the bodymember. With the body member I, ring sectors 3 and plug I0 assembled asindicated, pins II are each adjusted and then secured as by respectiveset screws I5 with said pins in contact with body member I so that athree-point support is thereby provided which prevents accidentaldisarrangementof the several parts during the subsequent application ofsolder to make the assembly permanent.

Means for producing thread forms on the circular ring sectors 3 by alapping operation include a hollow holder II, having at one end a nutreceiving socket I8, with its outer end enlarged to form shoulder I9,and with a keyway provided at 20. At the opposite end, holder I1 isdiametrically enlarged to provide for a chuck receiving socket H. Toreduce weight of holder I! and to render parts therewithin visible andaccessible, the peripheral wall of the holder is cut away to formopenings 22.

A nut 23 seated on shoulder 19 of socket i8, is keyed to the holder ITat 24 and held therein against relative longitudinal movement by cap 25which is screw threaded onto the holder. Engaged with nut 23 is a leadscrew 25, terminating at one end in a shank 21 and provided at itsopposite end with a socket 23 to receive split bushing 29 operable byscrew 30 to clamp and rigidly secure in axial alignment with the leadscrew 25 a lapping tool 3|. For split bushing 23 there may besubstituted others with bores of difierent diameter appropriate for therespective shanks of lapping tools of such diameter as may be required.

Within the socket 2| of holder I1 is seated chuck body 32 which isprovided with recess 34 r 3'! to thereby form radially extendingchannels as 38. In each channel 38 is movably fitted a shoe 39, andbetween the shoe. and peripheral wall 45 of the holder is placed acoiled spring 4|, operable to yieldably urge the shoe toward a centralaxis which coincides with the central axis about which the lead screwand lapping tool with respect to the holder are adapted to be rotated.Each shoe 39 is provided with a peripheral wall 42 facing 'said centralaxis. This wall is provided with a relief notch 43 and on opposite sidesthereof with beveled corners 44 which serve to limit peripheral wall 42to desirable bearing areas for engagement with a ring sector 3. Insertedat the innermost apex of each block 35 is a respective stop pin 45.These pins serve a purpose that will presently become apparent. As ameans to hold the several chuck elements described accurately seatedwithin chuck body 32, there may be employed a cover plate 46, slotted asat 41 to receive screws 48 and with the slots enlarged as at 59 toprovide for facility in re- 'moving' the cover when the screws areslightly loosened. Serving to removably secure the chuck assemblydescribed against longitudinal or rotative movement within its socket 2|of holder l1, set screw 53 and key pin are interposed between the chuckbody and holder. Thus the chuck assembly may be removed from the holderfor use independently thereof and concerning which there will followfurther explanation.

The shank 21 of lead screw 26 is adapted to be held in a chuck as 52,carried by a reversibly driven spindle (not shown). With the lead screwthus driven while holder I! is held against rota tion, the latter iscaused to move back and forth longitudinally of the coincident axes ofthe lead screw and lapping tool, which of course are suitably threadedto correspond to a pitch of thread which it is desired to have formed ina set of circular ring sectors 3. Each one of a set of sectors is placedbetween a respective shoe 39 and the lapping tool 3| (see Fig. 6). Thesectors while in this arrangement are each urged against the lappingtool by their respective spring backed shoe; 'After a comparativelybrief period of the action indicated and just described, a helicalgroove is formed in the ring sectors 3 by abrasive effect ofthe threadedlapping tool. When this grooveis-forrned to a-slight depth it issufiicient to establish relative longitudinal movement between, the ringsectors and the chuck assembly as a whole, and the lapping tool, withoutassist- 4 ance of the leading eirect initially required and. imparted bythe lead screw. In other words the chuck assembly together with theslightly grooved ring sectors held therein, may be removed from theholder I! and transferred to an automatic machine for continuedapplication of the lapping operation which may proceed with a successiveuse of lapping tools of respective suitably different diameters tocompensate for wear on each tool prior to the final one used. Thecontour of each successive tool used may also be different as may berequired to produce the finally desired profile, such for example asthat shown in Fig. 6. Asthe eiiect of abrasive action of the lappingtools upon the ring sectors progresses during relative rotary andlongitudinal movement therebetween, the sectors are advanced by thespring urged shoes until they engage respective stop pins es. Thelocation of these stop pins is such that when a ring sector has movedinto position to engage them said sector is then sub-'- stantiallyconcentric to the axis'of the threaded lapping tool, which signifiesthatthread formation on the sector is completed to within a fewthousandths of an inch of the required depth. Thus when each sector of aset being lapped has been arrested by engagement with stop pins as, itis thereby indicatedthat the lapping opera tion is substantiallycompleted and the ring sec-' tors are in readiness for assembly with abody a member in accordance with the method of assembly as aboveexplained. Subsequently slight further lapping is applied to the sectorsin the permanently assembled gauge to impart thereto the I form or ringgauge thread employed for testing screw threads of American Nationalform is shown in enlarged profile in Fig. 11 where it is indicatedtogether with maximum diameter clearance space as at 53, this particularform being widely accepted practice in the manufac'-- ture of threadring gauges. 1

ing, sintering or grinding to create thread for-ms within bores ofrelatively small diameter.

Having thus described our invention what we claim is:

l. Mechanism for producing siinul'taneouslyby V a lapping tool, threadforms upon a plurality of circular ring sectors .whichare adapted whens0 threaded to be mounted in a body member to form a thread ring gauge,said mechanism in cluding in combination, a holder, a nut, achuck', saidnot and chuck being co'axiall'y supported by the holder respectively atopposite ends-there; 2

radially extended from its central axis and in-.

eluding a follower shoe in. each channel, each shoe being adapted tobear upona circular ring sector interposed between said! shoehandfthjethreaded lapping. tool, 'and means 'for yiemablv' urging teach. shoetoward the axis ofltlie chuck". to oorrespondinglypress' a" respectivecircular 5. ring sector upon the threads of the lapping tool duringrelative reciprocatory and rotary movement between the lapping tool andholder.

2. Mechanism for producing simultaneously by a lapping tool, threadforms upon a plurality of circular ring sectors which are adapted whenso threaded to be mounted in a body member tdform a thread ring gauge,said mechanism including in combination, a holder, a nut, a chuck, saidnut and chuck being coaxially supported by the holder respectively atopposite ends thereof, a lead screw engaged by thenut, a threadedlapping tool rigid with the lead screw, extended longitudinally throughthe chuck and coaxial therewith, said chuck having channels thereinradially extended from its central axis and including a follower shoe ineach channel, each shoe being adapted to bear upon a circular ringsector interposed between said shoe and the threaded lapping tool, meansfor yieldably urging each shoe toward the axis of the chuck tocorrespondingly press a respective circular ring sector upon the threadsof the lapping tool during relative reciprocatory and rotary movementbetween the lapping tool and holder, and stop means for limitingmovement of the circular ring sectors eiiected by movement of respectiveshoes. 3. Mechanism for producing simultaneously by a lapping process,thread forms upon a plurality of circular ring sectors which are adaptedwhen so threaded to be mounted in a body member to form a thread ringgauge, said mechanism including in combination, a substantiallycylindrical hollow holder having a nut receiving socket at one end and achuck receiving socket at the opposite end, a nut, means for removablyholding the nut in its socket in the holder, a chuck, means forremovably holding the chuck in its socket in the holder, a lead screwengaged by the nut, a threaded lapping tool removably secured in rigidrelation with the lead screw, extending longitudinally through the chuckand coaxially therewith, said chuck including a recessed body, blockssuitably arranged and secured in the recess of the chuck body therebyproviding channels radially extended from the central axis of the chuck,and a follower shoe in each channel, each shoe being adapted to bearupon a circular ring sector interposed betweensaid shoe and the threadedlappin tool, means for yleldably urging each shoe toward the axis of thechuck to correspondingly press a respective circular ring sector uponthe threads of the lapping tool during relative reciprocatory and rotarymovement between the lapping tool and holder, and stop means forlimiting movement of the circular ring sectors effected by movement ofrespective shoes.

4. Mechanism for simultaneously producing by a lapping operation, threadforms upon a plurality of circular ring sectors with the threads formedon each section correlated to the threads formed on the other sectorswhereby the several sectors when suitably secured in a body member forma'thread ring gauge, said mechanism in cluding in combination, athreaded lapping tool, a support for maintaining a plurality of circularring sectors in coplanar relation around the lapping tool, means foryieldably urging the sectors to move toward the rotational axis of thelapping tool in respective radial paths while maintained in coplanarrelation and normal to said axis, and stops extended from the supportand adapted to engage adjacent and surfaces of respective sectors toprevent radial movement of the sectors beyond a predetermined limit.

5. Mechanism for producing by a lapping operation, thread forms upon aplurality of circular ring sectors with the threads formed on eachsector correlated to the threads formed on the other sectors whereby theseveral sectors when suitably secured in a body member form a threadring gauge, said mechanism. including, a chuck, a threaded lapping toolextended longitudinally through the chuck and coaxial therewith, meansfor rotating and reciprocating the lapping tool relative to the chuck,said chuck having'channels therein radially extended from the coincidentaxes of the lapping tool and chuck, follower shoe confined in eachchannel for radial movement only, each shoe being engageable with acircular ring sector interposed between said shoe and the lapping tool,and means urging each slice toward the lapping tool.

6. Mechanism for producing by a lapping operation, thread forms upon aplurality of circular ring sectors with the threads formed on eachsector correlated to the threads formed on the other sectors whereby theseveral sectors when suitably secured in a body member form a threadring gauge, said mechanism including a chuck, a threaded lapping toolextended longitudinally through the chuck and coaxial therewith, meansfor rotating the lapping tool relative to the chuck, said chuck havingchannels therein for guiding respective circular ring sectors indefinite radial paths while said sectors are in coplanar relation, afollower shoe confined in each channel for radial movement only, eachshoe being engageable with a circular ring sector interposed betweensaid shoe and the lapping tool, and means for independently urging eachshoe toward the lapping tool.

7. Mechanism according to claim 6 also including, stops extendedradially from the chuck in proximity to the lapping tool, said stopsbeing adapted to engage adjacent end surfaces of respective sectors toprevent radial movement of he sectors beyond a predetermined limit.

8. Mechanism for producing by a lapping operation, thread forms upon aplurality of circular ring sectors with the threads formed on eachsector correlated to the threads formed on the other sectors whereby theseveral sectors when suitably secured in a body member form a threadring gauge, said mechanism including a threaded lapping tool, a supportfor the circular ring sectors arranged to confine movement of saidsectors to a plane substantially normal to an axis about which thelapping tool and the support are relatively rotatable, means foryieldably urging said sectors radially against the lapping tool, andstops extended from the support for limiting movement of said sectors.

9. Mechanism for producing by a lapping operation, thread forms upon aplurality of circular ring sectors with the threads formed on eachsector correlated to the threads formed on the other sectors whereby theseveral sectors when suitably secured in a body member, form a threadring gauge; said mechanism including a chuck, a threaded lapping toolextended longitudinally through the chuck and coaxial therewith, meansfor rotating and reciprocating the lapping tool relative to the chuck,said chuck having channels therein radially extended from the coincidentaxes of the lapping tool and chuck, a follower shoe confined in eachchannel for radial movement only, each shoe being engageable with acircular ring sector interposed between said 7 shoe-and the lappingtool, a plate secured to the chuck and overlying the channels, and meanswithin each channel for urging, the shoe therein toward the lappingtool.

, ALVIN E. LANGMAID.

ROBERT A. BLOOM.

- REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Dane Number Kawa-hara Apr. 6, 1909 Number

